Question

Choo Kheng must travel at least 288

kilometers in a submarine in order to reach her destination. The submarine travels at a constant speed on the water's surface, and travels at a constant speed underwater. In the given inequality, S

represents the number of hours the submarine can travel on the water's surface and U

represents the number of hours it can travel underwater in order to reach Choo Kheng's destination. If the submarine travels for 2 2/3


hours on the water's surface, what is the least number of hours the submarine must travel underwater in order for Choo Kheng to reach her destination?

Answer 1

Let's break down the information given in the problem:

Distance to be traveled: at least 288 kilometers
Submarine speed on water's surface: constant
Submarine speed underwater: constant
Hours traveled on water's surface: 2 2/3 hours

Let's represent the distance traveled on water's surface as 2 2/3S and the distance traveled underwater as US. Since the total distance must be at least 288 kilometers, we can write the following inequality:

2 2/3S + US ≥ 288

Now, we know that the submarine travels at a constant speed both on the water's surface and underwater. This means that the time spent traveling on each surface is directly proportional to the distance traveled on that surface. Therefore, the time spent traveling underwater (U) must be equal to 3 times the time spent traveling on the water's surface (2 2/3).

U = 3 * (2 2/3) = 8 hours

So, the least number of hours the submarine must travel underwater in order for Choo Kheng to reach her destination is 8 hours.